Dissolved oxygen and the temperature of water
Sub-atomic particles are more active at higher temperatures, resulting in oxygen atoms breaking their molecular bonds. Water is composed of one hydrogen atom and two oxygen atoms. Once the atomic bond is broken, the oxygen atoms break free, resulting in there being less oxygen in the water. At cooler temperatures, there is less activity at the atomic level; hence, oxygen is retained in the water. At the other extreme, all oxygen is lost when water is boiled. Some warm water fish species have adapted to lower levels of oxygen in water, by obtaining additional oxygen from the atmosphere.
This science fair project involves an electric aquarium heater and water as well as chemicals contained in the water quality kit. Appropriate care should be taken to avoid injuries.